Wiring (Ringmain)

[Bobbya82]

Hi Guys can you confirm that the wiring diagram is ok?

Thanks
UPDATED
Ringmain
Dual box is slightly bigger than a double socket it houses 2 single sockets

1= https://www.screwfix.com/app/sfd/cat/pro.jsp?ts=74439&id=13479
3amp fuse for fan

2= https://www.screwfix.com/app/sfd/cat/pro.jsp?ts=74043&id=13014

3= https://www.screwfix.com/app/sfd/cat/pro.jsp?ts=74482&id=80093
this is fused via the plugged in plug.

 

[pcboffinuk]

Hi Guys can you confirm that the wiring diagram is ok?

Not as a wiring diagram, there are too few wires for a start and not enough information...

But as a logical diagram it works with a couple of caveats...

Is this a radial circuit? If so, and its protected by a 20A or less mcb then its ok, otherwise the switches should be fused switch units (most DP switches are rated to 20A I believe and shouldn't be used directly on a ring final circuit).

The fan may or may not need a separate fuse anyway, depending on type/rating, etc.

I can't comment further without knowing what is before the dual box, cable sizes etc.

Give us more information and we'll be happy to advise.

Gavin

 

[Bobbya82]

I have updated the original post.
1= https://www.screwfix.com/app/sfd/cat/pro.jsp?ts=74439&id=13479
3amp fuse for fan

2= https://www.screwfix.com/app/sfd/cat/pro.jsp?ts=74043&id=13014

3= https://www.screwfix.com/app/sfd/cat/pro.jsp?ts=74482&id=80093
this is fused via the plugged in plug.

 

[pcboffinuk]

Ok,

That is better, except I would say that item 2 cannot be a 20A switch, assuming the ringmain is on a 32A breaker.

If you replaced it with another item 1 with a 13A fuse then that's fine.

in fact you could lose one of the legs after the dual socket, and have the fan FCU as a spur from one single socket, and the Socket FCU as a spur from the other single socket, then connect the two sockets onto the ring.

It may be just as easy to wire it as you have it though.

If you did have item 2 as a spur, there is an argument that a 20A switch would be ok, since the cable can only take 20A anyway (and in turn the single socket 13A), but personally I would go with another switched FCU.

Other people may have their own thoughts...

Hope That Helps

Gavin

 

[Bobbya82]

Hi Thanks for your reply,

I assumed that socket 2 was ok as it feeds a socket that is then fused by the plug of the appliance 13A(oven)

 

[pcboffinuk]

In reality it's probably unlikely that there would ever be a problem, but its bad practise to rely on downstream protection - if there was an overload on the ring somewhere then more than 20A could pass through the switch and cause it to overheat.

Having said that, you could have a single socket to replace it, which in theory is only rated for 13A - but that's accepted practise for you

Other people may say it's fine, but if I was doing it I'd put in a switched FCU.



Gavin

 

[securespark]

And that leaves you with 2 fuses per appliance.

20A switch is fine because it is only switching how much?

As you say, a 13A accessory is used on a 32A circuit, but the point is that that 13A value is the rating of the accessory, not the maximum protective device.

A 20A switch will switch 20A safely. The maximum load as he has drawn the circuit will be 13A: no problem.